chem a level ocr

Iodine, I2, is a grey-black solid that is not very soluble in water.
Equilibrium 1 is set up with the equilibrium position well to the left.

I2(s) ⇌ I2(aq) Equilibrium 1
Solid iodine is much more soluble in an aqueous solution of potassium iodide, KI(aq), than in
water.
Equilibrium 2 is set up.

I2(aq) + I−(aq) ⇌ I3
−(aq) Equilibrium 2
A student dissolves I2 in KI(aq).
The resulting 200 cm3 equilibrium mixture contains:

4.00 × 10−5 mol I2(aq)
9.404 × 10−2 mol I−(aq)
1.96 × 10−3 mol I3
−(aq).
Calculate Kc for equilibrium 2.
Give your answer to an appropriate number of significant figure
i put these in kc equation however i had to times all values by 5 to get answer right why is this the case can someone help please